Preheat oven 350º F line cookie sheets with parchment paper or Silpat pads (not necessary but makes cleanup so easy.)
In a separate bowl, sift the flour, salt, and baking soda.
Cream butter, margarine, and sugars. Once that is well blended, add eggs and vanilla. Next, I add the nuts (optional) because it is more dispersed than adding at the end, which is when most recipes add them.
Next, with a mixer on low, SLOWLY add the flour mixture, 1/3 at a time. Once the flour mixture is incorporated, mix in the oatmeal.
Using a 1 1/2 to 2 Tbsp scoop, drop scoops of dough onto the lined cookie sheets. Dip your fingers in water and press each cookie ball to flatten slightly.
Bake 10 min and allow cookies to cool slightly in the pan. Once they've firmed up, remove to a wire rack to finish cooling.
NOTE: I use my Kitchenaide stand mixer. It really is the best tool for making cookies but a hand mixer is good also, just is hard on the gears.